Furnace



Patented Dec. 14, 1937 UNITED STATES PATENT OFFICE FURNACE William Raisch, New York, N.' Y., assignor to Underpinning & Foundation Co., Inc., New York, N. Y., a corporation of New York Ajmplication September 5, 1936, SerialNo. 99,627

' 12 laims. (01. 110-12) This invention relates to improvements in furnaces of the type in which material is'introduced at the top of a furnace and fallson a hearth and is then agitated and rabbled to one or more outlets by suitable rabbling devices.

Usually the-material to be treated is introduced intermittently into the furnace but in course of time it is'bound to fall on the rabbling device or devices, an occurrence which is undesirable for various reasons. For example, some of the matefrial'falling on a rabbling device will be retained to the hearth, it will not be in the same condition asthe material dropped directly on the hearth and rabbled directly to the outlet or outlets. As

a matter of fact the tendency would be for the material to' cake and harden on the rabbling devices, thus interfering with their operation and action and necessitating cleaning from time to time.

Although the undesirable feature of having material cake on the rabbling devices would occur in the use of any kinds of material, wet and sticky material, such as sewage sludge and the like,

0 therefore would not be so sticky; Furthermore the material is fed more regularly from one hearth to another and does not fall in substantial masses as it does on the uppermost hearth.

The principal object of the invention is to provide advantageous and efficient means to avoid the aforesaid and other difiiculties experienced in machines heretofore in use.

' Another object is to provide means for preventing material introduced at the top of the furnace from falling on a rabbling device. A further object is'to prevent the fall of material on a rabbling device, including one or more members positioned to obstruct the downward passage of such material as the rabbling device passes under ,the charging opening.

According. to a preferredjtmanner of carrying out the invention,theinvention is embodied in a furnace in which a rabbling device, extends radially from a vertical shaftand over a hearth beneath the same.

through an opening 16 in the top H.

on which the material falls from the charging opening in the top of the furnace. The prevention of the fall of "freshly charged material on the rabbling device may be effected through a hingeddoor device which may include one door only but 5 preferably has two doors. These doors may be counterbalanced and operatively connected so as to open and close simultaneously and through suitable connections'may be controlled by a cam mounted on the vertical shaft so that they will be closed during each passage of a rabbling device Thesupply of material to the cam-controlled door maybe controlled by a separate set of pivoted doors normally held in closed position by suitable counterbalancing means. In operation material is charged on the upper seto'fdoors and as soon as sufi'icientmaterial has fallen on these doors they openand the material drops to'the cam-controlled doors and .will ordinarily pass through the same unless prevented by the cam means as a rabbling device passes beneath the charging opening. As soon as the rabbling device passes the charging opening, the doors are released'from the cam control.

Other objects, features and advantages willappear upon consideration of the following description and of the drawing in which:

Figure 1 is a fragmentary horizontal section of a furnace embodying a preferred form of the present invention; and 3 Figure 2 is a section taken along the line 2-2 of Figure 1. Referring to the drawing, there is illustrated a furnace l0 comprising a top ll, a hearth l2 spaced downwardly therefrom, and a peripheral wall l3 supporting said'top H and said hearth'lZ. At the axis of the furnace is a vertical hollow shaft 14 extending through the central part of i5 and At the 40 opening [6, there may be provided a gas seal IT to prevent the passage of gases between the shaft 14 and. the edge of the top II around the opening l6.

In the compartmentrbetween the top H and the hearth l2, the shaft [4 may be; provided with one or-more rabbling devices l8, each of which comprises a radial arm l9 and blades 20 inclined a central discharge opening or outlet so that,,when the shaft 14 is rotated in clockwise direction as viewed in Fig. 1, the material is rabbled toward the central opening [5 to pass downwardly, for example to a lower hearth, not

shown; The top Il may be provided with a per a door device comprising two doors 24 mounted on shafts 25 and counterbalanced as by arms 28 and weights 2'3, so as to remain closed except when the Weight of material in the hopper 23 is sufiicient to open them.

According to the present invention, it is prothe distance between the doors 2 l'and the doors 28 is sufficient to have'greater capacity than the hopper 23, thus enabling the sets of doors to be more nearly independent in their action. The doors 28 may be caused to open and close simultaneously by intermeshing gear members or seetors 32 mounted on the shafts 29.

To hold the doors 23 closed when a rabbling device i8 is passing beneath the charging opening 2!, one of the shafts 29 may be provided with an arm 32 so fixed thereon that movement of the outer end thereof away from the axis of the furnace will close the doors and act to hold them closed. Such outward movement may be effected through a push member or link 33 pivoted to said outer end of the arm 32:and to the lower end of a downwardly extending arm .34 fixed on a shaft 35 rotatable in bearings 36 on a stationary frame above the top of the furnace. Fixed on the shaft 35 and extending downwardly therefrom is an arm 3i carrying on its lower end a roll 38 adapted to be engaged-and moved away from vertical shaft I4, by suitable cam means, to close the doors 2% and hold them in closed position.

Thecam means acting on the roll 38 may be of any desired form but, as illustrated, it comprises an annular cam member 39 encircling the upper part of the hollow shaft id and secured thereto. At its circumference or periphery the member 3315 provided with an upwardly projecting flange as which limits the outward movement of the roll 38 and consequently the upward movements of the doors 2%. Upward movement of the doors 28 to closed position'and locking of these doors in closed position may be effected by a cam it formed by an upwardly projecting flange and having an operating portion 42 for each rabbling device is of which three are indicated on the drawing. Each of these operating portions 52 may be considered as a separate cam and is provided with a gradually curved forward side adapted to move the roll 38 outwardly, an end portion or dwell to hold the roll 38 in its outermost position and a concave rear side arranged to permit free movement of the roll toward the shaft it as soon as the dwell portion moves out of contact with the roll. It will be evident that the flange EB might be omitted and that a stop in some other location may be used. One advantage of utilizing the flange or rim 4!) as a stop is that the flange is located close to the dwell portions of the operating cam portions 42 and it is therefore relatively easy to hold the roll 38 against radial movement between one of said dwell portions and the rim it. n

In operation of the furnace, the shaft is is rotated by any suitable means and the rabbling devices l8 above the hearth i2 act to agitate the material on the hearth and gradually work it to the central discharge opening or outlet I where it drops to another hearth not shown. Fresh material is supplied to the hopper 23 and when it accumulates to a sufficient extent the weight of the material opens the doors 24 against the action of the counterweights and the material flows into the space above the doors 28 which usually open in turn and permit the material to drop on the hearth 12. If, however, a rabbling device 18 is immediately beneath the charging opening the doors 28 are held closed and if a -rabbling device moves under the opening just after the doors 28 have opened these doors will be moved to closed position until the rabbling device has moved past the charging opening.

It should be understood that various changes may be made and that certain features may be used without others, without departing from the true spirit and scope of the invention;

.Having thus described my invention, I claim:

1. In an apparatus of the character described, the combination with a hearth, a charging device to drop material on said hearth and a rabbling device traveling between the charging device and the hearth and over all parts of the hearth on which the material is dropped, of

means for preventing material supplied by said charging device from being deposited on said rabbling device;

2. In an apparatus of the character described, the combination with a hearth, a charging device to drop material on said hearth and a rabbling device traveling so as to pass between the charging device and the hearth, of means for control- ;ling the charging device to prevent the dropping of material therefrom while the rabbling device is beneath the charging device.

3. In an apparatus of the character described, the combination with a furnace top having a charging opening, a hearth to receive material from said charging opening, means including a counterbalanced door for controlling the passage of material through said charging opening, a ra dially extending rabbling device above said hearth and traveling so as to pass beneath said charging openingof means holding said door closed while the rabbling device is passing the charging opening. 7

4. In a furnace of the character described, the combination with a furnace top having a charging opening, a hearth to receive material from said charging opening, means including a counterbalanced door for controlling the passage of to pass beneath said charging opening, of means for closing said door asthe rabbling device approaches the charging opening and holding the door closed while it is passing'the charging open- 5. In an apparatus of the character described, the combination with a furnace top having a charging opening, a hearth'to receive charged material, means including a counterbalanced pivotally mounted door for controlling the passage of material through said charging opening, a radially extending rabbling device beneath said furnace top and traveling so as to pass beneath said charging opening, of means holding said door closed while the rabbling device is passing the charging opening, the door-holding means including a cam moving with said rabbling device and a lever connected with said door and operable by said cam.

6. In an apparatus of the character described,

-a top, a chute extending through said top, a

the combination with a furnace top having a charging opening, a hearth beneath said opening to receive the material, means including a counterbalanced pivotally mounted door for controlling the passage of material through said charging opening, a plurality of radially extending rabbling devices over said hearth and traveling soas to pass beneath said charging opening, of means holding said door closed while the rabbling device is passing the charging opening, the door-holding means including a plurality of cams traveling with said rabbling devices and a lever connectedwith said door and engageable by ,said cams substantially 'at the times when the corresponding rabbling devices pass beneath said door.

'7. In an apparatus comprising a furnace chamber having a top, a chute extending through said top, a counterbalanced door device to control the passage of material through said chute, a hearth spaced downwardly from said top to provide a compartment therebetween, said hearth being provided with discharge means, a vertical shaft, and a rabble device over said hearth and operated by said shaft to travel beneath said chute and move the material on said hearth toward said discharge means, door-controlling weighted-door device to control the passage of material through said chute, a hearth spaced downwardly from said top to provide a compartment therebetween, said hearth being provided with discharge means, a vertical shaft, and a rabble device over said hearth and operated by said shaft to agitate the material on said hearth and gradually discharge it from the hearth, of a second counterweighted door device beneath the first-mentioned door device and means for preventing opening of said second counterweighted door device when the rabbling device is beneath the same.

9. In an apparatus of the character described, the combination with a furnace chamber having atop, a chute extending through said top, a Weighted-door device to control the passage of material from said chute, a hearth spaced downwardly from said top to provide a compartment therebetween, a vertical shaft, and a rabble de-' vice over said hearth and operated by said shaft to discharge the material from said hearth, of means for preventing opening of said counterweighted door device when the rabbling device is beneath the same. i

, 10. In an apparatus of the character described, the combination with a furnace chamber having counterbalanced-door device to control the passage of material from said chute, a hearth spaced downwardly from said top to provide a compartment therebetween, said hearth being provided with discharge means, a vertical shaft, and a rabble device over said hearth and operated by said shaft to move the material on said hearth toward said discharge means, of controlling means for preventing opening of said counterbalanced door device when the rabbling device is beneath the same, said controlling means comprising a cam follower connected with said counterbalanced-door device and a cam on said shaft having an operating part with a forward side adapted to force said cam follower away from the shaft and close the door device and an end in the form of a dwell to hold the door closed for the required period of time.

' 11. In an apparatus of the character described, the combination with a furnace chamber having a top, a chute extending through said top, a counterbalanced-door device to control the passage of material from said chute, a hearth spaced downwardly from said top to provide a compartment therebetween, said hearth being provided with discharge means, a vertical shaft, and a rabble device over said hearth and operated by said shaft to move the material on said hearth toward said discharge means, of controlling means for preventing opening of said counterbalanced door-device when the rabbling device is beneath the same, said controlling means comprising a cam follower connected with said counterbalanced door device, a cam on said shaft having an operating part with a forward side adapted to force said cam follower away from the shaft and close the door device and an end in the form of a dwell to hold the door closed for the required period of time, and a ring serving to limit the outward movement of the cam follower and serve as a stop for the door device,

12. In an apparatus of the character described, the combination with a furnace top having a charging chute, a hearth to receive material from said chute, chute-closing means including a pivoted door and counterbalancing means to hold the door closed until a sufficient amount of material to overcome the counterbalancing means accumulates on the door, a radial rabbling device rotating about the axis of the furnace and rection and thereby determine the closed position of the door.

WILLIAM RAISCH. 

